1. Field of the Invention
The invention relates in general to a slicer level calculator, and more particularly to a slicer level calculator adaptable to the signal to noise ratio (SNR) criterion and the co-channel interference criterion of an input video signal for changing the operation of computing the slicer level.
2. Description of the Related Art
The technology for restoring the obtained sync signal according to received image signal already exists. When the sync signal is a binary signal, the image signal has two different signal levels (high level and low level) in response to different logic values (logic value 1 and logic value 0). In the present example, the operation of restoring the sync signal from the image signal needs to correspondingly determine which component of the image signal corresponds to logic value 1 and which component of the image signal corresponds to logic value 0. In general, the operation for determining the logic value of the image signal is implemented by comparing the level of the image signal with the slicer level, such as the middle value between the blanking voltage level and the sync-tip voltage level of the image signal.
However, in practical application, the estimated slicer level often has low accuracy when the image signal has a low signal to noise ratio (SNR) or is under the influence of co-channel interference. As a result, the sync timing is too long and the error rate of the obtained sync signal is too high.